MAKE a HIGH VOLTAGE SUPPLY IN 5 MINUTES

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Introduction: MAKE a HIGH VOLTAGE SUPPLY IN 5 MINUTES

About: Make a better Instructable, and the world will beat a path to your website.
In this Instructable you will learn how to make a High Voltage High Frequency power supply in 5 minutes and for less than $20.

All you need is a compact fluorescent light (CFL) and a flyback transformer.

Flyback transformers are found in TVs and CRT monitors. They make the high voltage, high frequency current necessary to trace the electron beam across the screen. They are small and compact, and you can take them out from an old computer monitor or TV.

CFLs are very popular high efficiency fluorescent lights. They are similar to their ancestor the fluorescent light tubes but use electronic ballasts instead of the big and heavy ballasts in the old technology.

The electronic ballast works by generating high frequency currents that are fed to a tiny high frequency transformer that boost the voltage and run the fluorescent tube. It is the high frequency that makes the assembly compact.

The electronic ballast generates less than 1000 volts. But by replacing the fluorescent bulb of the CFL with a flyback transformer, spectacular voltages can be achieved.


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Step 1: Some Info on CFLs

CFLs can come in a variety of shapes and sizes. Generally the bigger the wattage the larger the voltage output. For this Instructable I got a 65 Watts light bulb.

Most CFLs have a similar circuit topology. All of them have 4 wires coming out of them. The wires are in pairs, and each pair connects to a filament inside the light bulb.

The CFLs I came across have the high voltage on the outer wires. You only need to connect the outer wires to the primary coil of the flyback transformer.

You will find a comprehensive description of CFL circuits on this page

Step 2: Some Info About Flyback Transformers

Flyback transformers come in all different shapes and sizes. Pick a big one.

The challenge with the flyback transformer is to find 3 pins out of 10 to 20 pins. One pin will be the high voltage ground the other two pins will be that of the primary coil that will connect to the CFL's electronic board.

If you can get the schematic of the flyback transformer that will save you time. However you can figure out the pins by following the instructions here.

Danger - if you are going to get the flyback from a TV or CRT you need to discharge it. It can hold a dangerous charge even days after the TV or CRT is turned off (see picture for details).

Step 3: The Finished Setup

This is how the finished high voltage supply looks like.

Remember, this is a DC supply. The output from the thick wire is positive. In TVs and CRTs this high voltage output drives the negative electrons from the filament to the screen.

If you need AC high voltage, you have to remove the built-in diode or find an old flyback transformer that does not have a built-in diode.

Step 4: Troubleshooting

The first time I build the circuit, it worked immediately. I used a 26 watt CFL.

Then I decided to get a bigger CFL and I build it exactly like the first circuit. It didn't work. I was disappointed. I thought that the CFL electronics were shot.

But when I reconnected the fluorescent tube to the four wires, the CFL worked again. I realized that this type of CFL circuit needed to "sense" the filaments in order to operate. Remember, I was only using the outer wires and leaving the two inner wires alone.

So I put a resistor across the outer wire and the inner wire. The circuit worked! But within seconds the resistor was in flames.

So I decided to use a capacitor in place of resistor. The capacitor allows AC currents but blocks DC while a resistor allow both AC and DC currents to flow through it. Also a capacitor does not heat up because it provides a low resistance path for AC currents.

The capacitor worked great! The arcs produced were very big and thick.

So in summary there two things that can go wrong:

1. You wired it wrong, either on the CFL side or the flyback side.
2. The CFL electronics needs to sense the filament and you can use a capacitor as a substitute.

Use a high voltage rated capacitor. Mine was 400V and I got it from another CFL circuit.

While troubleshooting, be very careful, you are dealing with very high voltages and high currents.

When soldering, disconnect the circuit from the power outlet.

Step 5: Disclaimer

The circuits in this Instructable use very high voltages and currents.

These currents and voltages are deadly! You can easily hurt yourself, as well. Build this circuit at your own risk.

This type of high frequency high voltage current is used in surgical cauterizers. So if you get shocked you will burn yourself and cut your flesh. There is also a considerable fire hazard from the circuit.

Use the Nikolai Tesla's safety techniques when working with high voltages:

1. Only use one hand (put your other hand on your lap or pocket)
2. Wear insulating shoes
3. Use a dead man stick or insulated pliers when touching or manipulating the circuit.
4. Use a power bar with a thermal fuse rather than sticking the circuit directly in the socket. This will limit the current that will go through your body.
5. When soldering, disconnect the circuit from the power outlet.

Generally, in electricity it is the the current that kills. if the currents are low there is little danger even if the voltages are very high (think of Tesla holding the his Tesla coil).

This circuit has high currents which makes it considerably dangerous.

a 65W CFL can deliver 65mA easily (65W/1000v).

And if you look at the picture below, at greater than 50mA the little guy is dead.

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955 Comments

0
handyman29
handyman29

10 years ago on Step 5

Is it 50mA or 50MA, because I don't think 0.05A is enough to kill someone. I would think 5A is enough to cause damage. I've worked with wires connected to 500mA sources and I am still here.

0
sglawrie25
sglawrie25

Reply 13 days ago

Just like the other replies say, it really depends where you are shocked, across the heart 50mA can easily kill you, but I have been shocked by the mains (UK 230V 13A) but as it was just on a finger, it hurt for a while but did not cause any major damage. Always use the one hand rule when dealing with high voltage or current, even if the circuit is off.

0
DeusXMachina
DeusXMachina

Reply 10 years ago on Introduction

It's 50mA, across the *heart*. Remember Ohm's law, I = V/R. A 12v car battery is capable of producing several amps peak current. However, the resistance from one hand to the other is around a few thousand ohms. So, it is possible to grab both terminals of a car battery, contrary to what you see in movies. You need enough volts to push pass the resistance, AND just enough current to move through the heart, to risk electrocution. Wall voltage is enough to do it, and definitely some parts of this circuit are able to.

0
jimmie.c.boswell
jimmie.c.boswell

Reply 5 years ago

factors affecting body resistance, sweat, humidity, sea water, chlorinated water, ac or dc. the lowest voltage, reportedly causing death is 6V dc. so do, you feel lucky? the body skin resistance, can change according to the situation. and of course once the initial punch through talks place, resistance is dramatically decreased.

plus there are the other effects, of physical clamping or vaulting. which can cause, physical trauma that can cause death or injury. but at 50ma, flash burn would not be a factor. but as voltage increases, the possibility of soft x-rays becomes greater and depending on the type of targets used such as tungsten. and at 50kv you are, entering medium x-ray electron volt range. which is only briefly, for the arc start period.

and remember in short circuit conditions, voltage decreases and amps increase. so your 50ma could quite possibly become, 100 ma sufficient to stop the heart of cause fibrillation or freeze the lungs causing suffocation in case of clamp on. because of the two scenarios of either freeze or being thrown away. if your muscles contract you freeze, if they expand your kicked away.

this all plus, the danger is not necessarily over after being shocked. since people have died, even after a week of being shocked and only thought, they were ok. so it is best to minimize the risk, of receiving any shock to 0 chance.

0
ApprenticeWizard
ApprenticeWizard

Reply 10 years ago on Step 5

Something else to note: the 20mA range can be more dangerous than the 50mA range. 20mA will disrupt the heart's operation (even with current removed), leading to a potentially painful death. 50mA+ clamps the heart; remove the current and the heard will resume pumping.

Again, this is lethal Primarily if the current path crosses the heart. Those who have worked with (and even taken) more current and still post here did not have a current path across the chest.

A simple and effective precaution when working around high voltages is to always keep one hand in your pocket: worrisome situations occur when one hand is grounded and the other is touching a hot lead.

0
tristantech
tristantech

Reply 10 years ago on Introduction

yes, you are absolutely right. Thanks for clearing this up.

0
skrubol
skrubol

Reply 10 years ago on Introduction

5-10mA is enough to kill, but it's not likely to. I've been hit by 9kV, 30mA, as well as shocked myself multiple times with 120V house current (on a 10+A fuse,) and I'm still here. That doesn't mean either of those situations can't kill you.

0
Jimmy Proton
Jimmy Proton

Reply 10 years ago on Introduction

wow, what does 9kV feel like? i got shocked by a camera cuz i touched the switch oart and it burnt a little hole in my finger but thats only a few hundred volts

0
skrubol
skrubol

Reply 10 years ago on Introduction

It was probably only 4.5kV because it was to the center tap, but it didn't really hurt. Just made me really tired. Your hit probably had a lot more current than 30mA. A cap can deliver amps

0
BOOM5601
BOOM5601

Reply 10 years ago on Introduction

But arent the caps in cameras only something like 30mA?

0
handyman29
handyman29

Reply 10 years ago on Introduction

NOOOOO! caps in camera's are usually 6000uf or more depending on how big the camera is or the flash type. That is probably close to half an amp because of the high current capacitance. The voltage is only 1.5v but the current is very high.

0
Jimmy Proton
Jimmy Proton

Reply 10 years ago on Introduction

what are you talking about, camera caps are 330v 120uf.

0
handyman29
handyman29

Reply 10 years ago on Introduction

What am I talking about? What are you talking about? A capacitor is measured in farads, not volts. One farad is one coulomb which is 6.25x10^18 electrons. Amperage is the measure of how many coulombs of current cycle in one second, so since capacitors accept certain amounts of coulombs, that must mean that capacitors store current, not voltage. How or why would camera designers integrate a cap rated for 330 volts, when only a 1.5 - 3v battery is used, but only store 120uf of current. The greater the farad, the bigger the flash. Maybe your camera has that, no way for me to know.

0
Jimmy Proton
Jimmy Proton

Reply 10 years ago on Introduction

ALL capacitors have a rating for voltage and farads

0
handyman29
handyman29

Reply 10 years ago on Introduction

Yes your right there, but making a cap rated for 330 Volts will just make it physically larger, nothing else. They are almost always set to 10 or 16 Volts to keep physical dimensions smaller. The farad rating is what affects it's performance, the greater the farad, the longer it takes to charge, but makes a bigger bang.

0
Tesla_cool_maniac
Tesla_cool_maniac

Reply 5 years ago

No, ive seen 400 volt 330 uf caps small enough to fit into drinking straws, its what they use as the dielectric that truly determines voltages, not size, and most flash cameras have a step up circuit that outputs 309+ volts to charge caps

0
skrubol
skrubol

Reply 10 years ago on Introduction

I think your math for charge is off. 1 Farad is not 1 coulomb, it's 1 coulomb/volt. The amount of charge in a cap is the capacitance * voltage. Caps store voltage. If you charge a cap to 10v, wait a bit, and measure it's voltage, it'll still be roughly 10v. Inductors store current.
Caps are sized according to both their voltage and capacitance, roughly at k*c*v^2 (k being a constant for a given type of cap.) For the same capacitance, a 330v cap would be roughly 48,000 times larger than a 1.5v cap (ignoring the fact that you can only make a cap so small.)
Flashes use DC-DC converters, usually flyback or something similar to convert the low 1.5-7.6v supplied by the batteries into the hundreds of volts necessary to make a strobe work.

0
joaniehook
joaniehook

Reply 5 years ago on Introduction

What I have seen in later models of flash circuits is a series of discreet, diode voltage doublers to get the proper output high voltage. They are a lot cheaper to make than a fly-back transformer -- and also have the advantage of being much smaller and lighter by not requiring a lot of windings of copper wire.

As to inductive storage of potential, one of the worse, unanticipated shocks I ever got was from continuity testing of a war surplus, oil-filled filter choke I used to make a power supply for a 1.5kW, 40-10 meter linear amplifier. I was using a VTVM, which supplies 1.5V DC on the times 1 resistance scale. As my alligator clip was demised, I was holding the test leads in place with my fingers. When I removed the first test probe from the choke, the field collapsed and I got a jolt that was quite a bit more than I expected.

Keep it in mind that the potential voltages, from both capacitors and inductors, can be much higher than anticipated -- far exceeding the charge voltage. Also keep it in mind that when the skin threshold of human skin is exceeded, the apparent resistance will diminish a lot more than anticipated as the skin will form a trail of ionized salt water along the path of conductance.

0
maxpush99
maxpush99

Reply 10 years ago on Step 5

thats exacky right
caps store voltage
size depend on storage capabilty which is rated in farads
current does not matter
capera caps are tiny , rated in hundreds of volts and a few microfarads